#include "zuc_common.h"

static uint8_t S0[256] = {
    0x3e, 0x72, 0x5b, 0x47, 0xca, 0xe0, 0x00, 0x33, 0x04, 0xd1, 0x54, 0x98,
    0x09, 0xb9, 0x6d, 0xcb, 0x7b, 0x1b, 0xf9, 0x32, 0xaf, 0x9d, 0x6a, 0xa5,
    0xb8, 0x2d, 0xfc, 0x1d, 0x08, 0x53, 0x03, 0x90, 0x4d, 0x4e, 0x84, 0x99,
    0xe4, 0xce, 0xd9, 0x91, 0xdd, 0xb6, 0x85, 0x48, 0x8b, 0x29, 0x6e, 0xac,
    0xcd, 0xc1, 0xf8, 0x1e, 0x73, 0x43, 0x69, 0xc6, 0xb5, 0xbd, 0xfd, 0x39,
    0x63, 0x20, 0xd4, 0x38, 0x76, 0x7d, 0xb2, 0xa7, 0xcf, 0xed, 0x57, 0xc5,
    0xf3, 0x2c, 0xbb, 0x14, 0x21, 0x06, 0x55, 0x9b, 0xe3, 0xef, 0x5e, 0x31,
    0x4f, 0x7f, 0x5a, 0xa4, 0x0d, 0x82, 0x51, 0x49, 0x5f, 0xba, 0x58, 0x1c,
    0x4a, 0x16, 0xd5, 0x17, 0xa8, 0x92, 0x24, 0x1f, 0x8c, 0xff, 0xd8, 0xae,
    0x2e, 0x01, 0xd3, 0xad, 0x3b, 0x4b, 0xda, 0x46, 0xeb, 0xc9, 0xde, 0x9a,
    0x8f, 0x87, 0xd7, 0x3a, 0x80, 0x6f, 0x2f, 0xc8, 0xb1, 0xb4, 0x37, 0xf7,
    0x0a, 0x22, 0x13, 0x28, 0x7c, 0xcc, 0x3c, 0x89, 0xc7, 0xc3, 0x96, 0x56,
    0x07, 0xbf, 0x7e, 0xf0, 0x0b, 0x2b, 0x97, 0x52, 0x35, 0x41, 0x79, 0x61,
    0xa6, 0x4c, 0x10, 0xfe, 0xbc, 0x26, 0x95, 0x88, 0x8a, 0xb0, 0xa3, 0xfb,
    0xc0, 0x18, 0x94, 0xf2, 0xe1, 0xe5, 0xe9, 0x5d, 0xd0, 0xdc, 0x11, 0x66,
    0x64, 0x5c, 0xec, 0x59, 0x42, 0x75, 0x12, 0xf5, 0x74, 0x9c, 0xaa, 0x23,
    0x0e, 0x86, 0xab, 0xbe, 0x2a, 0x02, 0xe7, 0x67, 0xe6, 0x44, 0xa2, 0x6c,
    0xc2, 0x93, 0x9f, 0xf1, 0xf6, 0xfa, 0x36, 0xd2, 0x50, 0x68, 0x9e, 0x62,
    0x71, 0x15, 0x3d, 0xd6, 0x40, 0xc4, 0xe2, 0x0f, 0x8e, 0x83, 0x77, 0x6b,
    0x25, 0x05, 0x3f, 0x0c, 0x30, 0xea, 0x70, 0xb7, 0xa1, 0xe8, 0xa9, 0x65,
    0x8d, 0x27, 0x1a, 0xdb, 0x81, 0xb3, 0xa0, 0xf4, 0x45, 0x7a, 0x19, 0xdf,
    0xee, 0x78, 0x34, 0x60,
};

static uint8_t S1[256] = {
    0x55, 0xc2, 0x63, 0x71, 0x3b, 0xc8, 0x47, 0x86, 0x9f, 0x3c, 0xda, 0x5b,
    0x29, 0xaa, 0xfd, 0x77, 0x8c, 0xc5, 0x94, 0x0c, 0xa6, 0x1a, 0x13, 0x00,
    0xe3, 0xa8, 0x16, 0x72, 0x40, 0xf9, 0xf8, 0x42, 0x44, 0x26, 0x68, 0x96,
    0x81, 0xd9, 0x45, 0x3e, 0x10, 0x76, 0xc6, 0xa7, 0x8b, 0x39, 0x43, 0xe1,
    0x3a, 0xb5, 0x56, 0x2a, 0xc0, 0x6d, 0xb3, 0x05, 0x22, 0x66, 0xbf, 0xdc,
    0x0b, 0xfa, 0x62, 0x48, 0xdd, 0x20, 0x11, 0x06, 0x36, 0xc9, 0xc1, 0xcf,
    0xf6, 0x27, 0x52, 0xbb, 0x69, 0xf5, 0xd4, 0x87, 0x7f, 0x84, 0x4c, 0xd2,
    0x9c, 0x57, 0xa4, 0xbc, 0x4f, 0x9a, 0xdf, 0xfe, 0xd6, 0x8d, 0x7a, 0xeb,
    0x2b, 0x53, 0xd8, 0x5c, 0xa1, 0x14, 0x17, 0xfb, 0x23, 0xd5, 0x7d, 0x30,
    0x67, 0x73, 0x08, 0x09, 0xee, 0xb7, 0x70, 0x3f, 0x61, 0xb2, 0x19, 0x8e,
    0x4e, 0xe5, 0x4b, 0x93, 0x8f, 0x5d, 0xdb, 0xa9, 0xad, 0xf1, 0xae, 0x2e,
    0xcb, 0x0d, 0xfc, 0xf4, 0x2d, 0x46, 0x6e, 0x1d, 0x97, 0xe8, 0xd1, 0xe9,
    0x4d, 0x37, 0xa5, 0x75, 0x5e, 0x83, 0x9e, 0xab, 0x82, 0x9d, 0xb9, 0x1c,
    0xe0, 0xcd, 0x49, 0x89, 0x01, 0xb6, 0xbd, 0x58, 0x24, 0xa2, 0x5f, 0x38,
    0x78, 0x99, 0x15, 0x90, 0x50, 0xb8, 0x95, 0xe4, 0xd0, 0x91, 0xc7, 0xce,
    0xed, 0x0f, 0xb4, 0x6f, 0xa0, 0xcc, 0xf0, 0x02, 0x4a, 0x79, 0xc3, 0xde,
    0xa3, 0xef, 0xea, 0x51, 0xe6, 0x6b, 0x18, 0xec, 0x1b, 0x2c, 0x80, 0xf7,
    0x74, 0xe7, 0xff, 0x21, 0x5a, 0x6a, 0x54, 0x1e, 0x41, 0x31, 0x92, 0x35,
    0xc4, 0x33, 0x07, 0x0a, 0xba, 0x7e, 0x0e, 0x34, 0x88, 0xb1, 0x98, 0x7c,
    0xf3, 0x3d, 0x60, 0x6c, 0x7b, 0xca, 0xd3, 0x1f, 0x32, 0x65, 0x04, 0x28,
    0x64, 0xbe, 0x85, 0x9b, 0x2f, 0x59, 0x8a, 0xd7, 0xb0, 0x25, 0xac, 0xaf,
    0x12, 0x03, 0xe2, 0xf2,
};

/// @brief Msb16(n1)||Lsb16(n2)
static inline uint32_t construct_hl(uint32_t n1, uint32_t n2) {
    return ((n1 & 0x7FFF8000) << 1) | (n2 & 0xFFFF);
}

/// @brief Lsb16(n1)||Msb16(n2)
static inline uint32_t construct_lh(uint32_t n1, uint32_t n2) {
    return ((n1 & 0xFFFF) << 16) | (n2 >> 15);
}

/// @brief 比特重组
static void bit_reconstruction(uint32_t x[4], ZUC_CTX* zuc_ctx) {
    uint32_t* s = zuc_ctx->lsfr;
    // X0 = s15H || s14L
    x[0] = construct_hl(s[15], s[14]);
    // X1 = s11L || s9H
    x[1] = construct_lh(s[11], s[9]);
    // X2 = s7L || s5H
    x[2] = construct_lh(s[7], s[5]);
    // X3 = s2L || s0H
    x[3] = construct_lh(s[2], s[0]);
}

/// @brief LSFR初始化模式
static void lsfr_init(uint32_t u, ZUC_CTX* zuc_ctx) {
    uint32_t* s = zuc_ctx->lsfr;

    uint64_t v = (uint64_t)s[0];
    v += (uint64_t)s[0] << 8;
    v += (uint64_t)s[4] << 20;
    v += (uint64_t)s[10] << 21;
    v += (uint64_t)s[13] << 17;
    v += (uint64_t)s[15] << 15;
    v += (uint64_t)u;

    v = (v & 0x7fffffff) + (v >> 31);
    v = (v & 0x7fffffff) + (v >> 31);

    for (int i = 0; i < 15; i++) {
        s[i] = s[i + 1];
    }
    s[15] = (uint32_t)v;
}

/// @brief LSFR初始化模式
static void lsfr_work(ZUC_CTX* zuc_ctx) {
    uint32_t* s = zuc_ctx->lsfr;

    uint64_t v = (uint64_t)s[0];
    v += (uint64_t)s[0] << 8;
    v += (uint64_t)s[4] << 20;
    v += (uint64_t)s[10] << 21;
    v += (uint64_t)s[13] << 17;
    v += (uint64_t)s[15] << 15;

    v = (v & 0x7fffffff) + (v >> 31);
    v = (v & 0x7fffffff) + (v >> 31);

    for (int i = 0; i < 15; i++) {
        s[i] = s[i + 1];
    }
    s[15] = (uint32_t)v;
}

#define rotl(n, s) ((n << s) | (n >> (32 - s)))
static uint32_t F(uint32_t x0, uint32_t x1, uint32_t x2, ZUC_CTX* zuc_ctx) {
    ZUC_CTX* ctx = zuc_ctx;
    // W = X0^R1 + R2
    uint32_t w = (x0 ^ ctx->r1) + ctx->r2;
    // W1 = R1^X1, W2 = R2^X2
    uint32_t w1 = ctx->r1 + x1;
    uint32_t w2 = ctx->r2 ^ x2;

    uint32_t t1 = (w1 << 16) | (w2 >> 16);
    t1 = t1 ^ rotl(t1, 2) ^ rotl(t1, 10) ^ rotl(t1, 18) ^ rotl(t1, 24);
    ctx->r1 = (S0[t1 >> 24] << 24) |           // S0(t[0])
              (S1[(t1 >> 16) & 0xff] << 16) |  // S1(t[1])
              (S0[(t1 >> 8) & 0xff] << 8) |    // S2(t[2]) = S0(t[2])
              (S1[t1 & 0xff]);                 // S3(t[3]) = S1(t[3])

    uint32_t t2 = (w2 << 16) | (w1 >> 16);
    t2 = t2 ^ rotl(t2, 8) ^ rotl(t2, 14) ^ rotl(t2, 22) ^ rotl(t2, 30);
    ctx->r2 = (S0[t2 >> 24] << 24) |           // S0(t[0])
              (S1[(t2 >> 16) & 0xff] << 16) |  // S1(t[1])
              (S0[(t2 >> 8) & 0xff] << 8) |    // S2(t[2]) = S0(t[2])
              (S1[t2 & 0xff]);                 // S3(t[3]) = S1(t[3])

    return w;
}

/// @brief 祖冲之算法ZUC初始化
void zuc_common_init(uint8_t* key, uint8_t* iv, ZUC_CTX* zuc_ctx) {
    // 16个15比特常量D
    static uint32_t D[16] = {
        0x44d7, 0x26bc, 0x626b, 0x135e, 0x5789, 0x35e2, 0x7135, 0x09af,
        0x4d78, 0x2f13, 0x6bc4, 0x1af1, 0x5e26, 0x3c4d, 0x789a, 0x47ac,
    };

    for (int i = 0; i < 16; i++) {
        // LSFR[i] = key[i] || D[i] || iv[i]
        zuc_ctx->lsfr[i] = (uint32_t)key[i] << 23 | D[i] << 8 | (uint32_t)iv[i];
    }

    zuc_ctx->r1 = 0;
    zuc_ctx->r2 = 0;

    uint32_t x[4];
    for (int i = 0; i < 32; i++) {
        bit_reconstruction(x, zuc_ctx);
        uint32_t w = F(x[0], x[1], x[2], zuc_ctx);
        lsfr_init(w >> 1, zuc_ctx);
    }

    bit_reconstruction(x, zuc_ctx);
    F(x[0], x[1], x[2], zuc_ctx);
    lsfr_work(zuc_ctx);
}

/// @brief 祖冲之算法产生一节拍32比特密钥
uint32_t zuc_common_next(ZUC_CTX* zuc_ctx) {
    uint32_t x[4];
    bit_reconstruction(x, zuc_ctx);
    uint32_t Z = F(x[0], x[1], x[2], zuc_ctx) ^ x[3];
    lsfr_work(zuc_ctx);
    return Z;
}
